The present invention relates to a control system for an internal combustion engine, and particularly to a control system for an internal combustion engine including electromagnetically driven intake valves and/or exhaust valves.
A control system for an internal combustion engine including intake valves and exhaust valves in each of which a valve body is electromagnetically driven by a spring and solenoids, characterized in that power consumption caused by operation of the solenoids upon start-up of the engine is reduced by making use of the resonance phenomenon of the spring, has been known, typically, from Japanese Patent Laid-open No. Hei 9-195736. Such a reduction in power consumption caused by operation of the solenoids is effective because, upon start-up of the engine, a power for operating the electromagnetically driven valve, which is supplied from only a battery because no power is supplied from an alternator thereto, is required to be made as small as possible. Another control system of the type making use of the resonance phenomenon, characterized in that a drive starting timing of a valve is determined depending on a crank angle position in order to prevent interference between the valve and a piston upon start-up of an engine, has been known, for example, in Japanese Patent Laid-open No. Hei 9-303122.
A further control system of a type in which initial attraction for closing all of electromagnetically driven intake valves and exhaust valves is executed before start-up of an engine and then the start-up of the engine is permitted in order to prevent interference between the valves and pistons, has been disclosed in Japanese Patent Laid-open No. Hei 8-170509.
The control system disclosed in Japanese Patent Laid-open No. Hei 9-195736 or Japanese Patent Laid-open No. Hei 9-302122 is advantageous in reducing the power consumption by making use of the resonance phenomenon of the spring; however, such a control system is disadvantageous in that since the operation of the valves is started while the starter is operated, the output current of the battery is increased, and accordingly, if the battery is degraded, the output voltage is reduced, to cause a possibility that it fails to certainly start up the engine.
The control system disclosed in Japanese Patent Laid-open No. Hei 8-170509 is advantageous in that since the closing operation, that is, the initial attraction for the valves is executed before the cranking of the engine is started, the initial attraction is not overlapped to the operation of the starter; however, such a control system is disadvantageous in that since all the valves are simultaneously closed, the output current of the battery is temporarily abruptly increased, and accordingly, the output voltage is reduced, to cause a possibility that it fails to sufficiently perform the initial attraction.